Generally, aromatic polyamides, polyamide-imides and polyimides are difficult to process and generally have low solubility. Some improvement in solubility has been achieved by preparing the polymers from bulky diamines or from dianhydrides containing 3 or more aromatic rings. (compare, for example, DT-AS No. 1,595,733 and DT-OS Nos. 2,009,739, 2,153,829, 2,257,996 and 2,321,513). However, these polymers either cannot be processed from the melt, or are difficult to process from the melt and, in some cases, have inadequate heat and/or chemical stability.
More recently Darms in U.S. Pat. No. 4,239,880 has disclosed polyamides, polyamide-imide and polyimide polymers prepared from exotic poly nuclear aromatic diamines. Although the polymers manufactured using Darm's diamines show improved solubility, these polymers do not form rigid rod polymers.
It, thus, appears desirable to produce polyamides, polyamide-imides and polyimides based on poly-phenylated diamines according to the present invention which would form soluble rigid-rod polymers having outstanding modulus, tensile and compression strength, excellent energy absorption characteristics, very low coefficient of expansion, excellent thermal stability, non-conduction, excellent film processability and relatively less expense that existing polymers. These properties will make the polymers ideally suited for use in the production of antiballistics, reinforced molecular composites, microelectronic coatings and gas, liquid and solid membrane separation applications.